1. Field of the Invention
The present invention relates to construction, and particularly to an expansive soil resistant foundation system that compensates for expansion and contraction of the expansive soil (ES) to provide a secure foundation resistant to potential cracking and failure due to such action.
2. Description of the Related Art
Any type of construction for various structures requires a strong and stable foundation, especially for buildings. The geography of a building site, however, may not always be ideal for a construction project.
For example, expansive soil ES presents a huge technical problem for civil engineers, architects, and other construction professionals. This type of soil is problematic because it can cause many construction problems and failures due to its characteristic behavior of swelling-shrinkage cycles between wet and dry conditions. Expansive soil ES tends to easily expand when exposed to water and to easily shrink when drying. The swelling and shrinkage behavior of the expansive soil ES produces unexpected pressure and stresses on a typical foundation system and structural elements, resulting in cracks and damage to structural components.
Some conventional solutions for handling expansive soil ES include (1) removing the expansive soil ES and replacing it with other non-expansive soil; (2) treating expansive soil ES by mixing it with some chemicals or such materials as lime, polymeric materials, or carton or polystyrene forms under the structure to absorb water; (3) avoiding construction on expansive soils; and (4) constructing short and lightweight buildings on deep foundations, such as pile systems with pile caps, piers or trenches.
The first method produces good results in most cases, but it is relatively costly and does not completely resolve the problem, since the danger still exists and may cause problems in the long run. The second method is difficult to implement or impractical, and the results are unsure. The third method merely avoids the problem and not a good solution, especially if there is insufficient area of non-expansive soils suitable for necessary construction. The fourth method is a costly and very expensive construction being applied to short and lightweight structures. The fourth method is usually more suitable for high rise and heavy structures, which already will not be affected much by expansive soil behavior.
Currently, there appears to be no permanent economical solution for construction on expansive soils that prevents the possibility of cracks and failure due to the swelling/shrinkage phenomenon. Moreover, there does not appear to be a solution that maintains a relatively even, temperate condition of the soil of the foundation, i.e., neither wet nor dry, at all times. Thus, an expansive soil resistant foundation system solving the aforementioned problems is desired.